JP6899736B2 - Cold storage - Google Patents

Description

The present invention relates to a cold storage provided with a heating device for preventing freezing of the storage.

For example, in an environment where the outside air temperature is lower than 0 ° C., such as in a cold region in winter, the temperature inside the low-temperature storage may drop to 0 ° C. or lower, and the storage in the storage may freeze. In order to prevent this freezing, it is disclosed and known in Patent Document 1, for example, that a heating device for heating the inside of the refrigerator at a low temperature is provided. In the vending machine of Patent Document 1, the on temperature (for example, 0 ° C.) and the off temperature (for example, 5 ° C.) of the heating device are set and input respectively, and when the internal temperature drops to the on temperature, the heating device is energized. When the temperature inside the refrigerator rises to the off temperature, the heating device is de-energized. Further, the vending machine of Patent Document 1 is provided with a timer for counting the current date and time, and is set so that the heating device is not energized in summer or the like when there is no risk of freezing of the stored items.

Japanese Unexamined Patent Publication No. 2000-251139

According to the vending machine of Patent Document 1 provided with a timer in addition to the heating device, it is possible to prevent unnecessary energization of the heating device in a preset season and reduce the power consumption of the device. .. However, the temperature during each season is not constant, and even in winter, for example, the temperature may rise to a temperature at which there is no risk of freezing of the storage. With the control method of Patent Document 1 for determining the necessity of a heating device based on the season, it is difficult to prevent unnecessary energization of the heating device on a high temperature day in winter or the like.

If an outside air temperature sensor that detects the outside air temperature of the low temperature storage is provided and the heating device is set to energize only when the outside air temperature is low, the above-mentioned problem of Patent Document 1 can be improved to some extent. However, the risk of freezing of the stored material is not determined only by the outside air temperature, and the risk of freezing differs depending on the heat insulating performance of the low temperature storage and the frequency of opening and closing the door. Therefore, the determination of the presence or absence of the risk of freezing based only on the outside air temperature is not always accurate. In addition, if an outside air temperature sensor is provided, the overall cost of the low temperature storage will increase accordingly.

An object of the present invention is to accurately determine whether or not there is a risk of freezing of a stored product, and when there is a risk of freezing, the heating device reliably prevents this, and when there is no risk of freezing, the heating device is used. The purpose is to provide a low temperature storage that can avoid unnecessary driving.

The low-temperature storage according to the present invention includes a cooling device 3 for cooling the internal R, a heating device 4 for preventing freezing to heat the internal R, and a temperature sensor 21 for detecting the internal temperature D. The operation mode includes a normal refrigerating mode in which the cooling device 3 is intermittently driven and an antifreezing mode in which the heating device 4 is intermittently driven. A predetermined first low temperature DL1 , a second low temperature DL2 lower than the first low temperature DL1, a predetermined first low temperature time TL1, and a second low temperature time TL2 shorter than the first low temperature time TL1 are set, respectively. In addition to the case where the temperature D inside the refrigerator detected by the temperature sensor 21 continues to be the first low temperature DL1 or less for the first low temperature time TL1 or more while the cooling device 3 is stopped in the normal refrigerating mode. In the normal refrigeration mode, even when the internal temperature D is the second low temperature DL2 or less and continues for the second low temperature time TL or more while the cooling device 3 is stopped, the mode shifts to the antifreeze mode. To do.

A first high temperature DH1 higher than the first low temperature DL1 and a predetermined first high temperature time TH1 are set respectively, and are detected by the temperature sensor 21 while the heating device 4 is stopped in the antifreeze mode. When the state in which the internal temperature D is the first high temperature DH1 or higher continues for the first high temperature time TH1 or higher, it is possible to take a form of returning to the normal refrigeration mode.

A second high temperature DH2 higher than the first high temperature DH1 and a second high temperature time TH2 shorter than the first high temperature time TH1 are set respectively, and in the antifreeze mode, the inside of the refrigerator is stopped while the heating device 4 is stopped. Even when the state where the temperature D is the second high temperature DH2 or higher continues for the second high temperature time TH2 or higher, it is possible to take a form of returning to the normal refrigeration mode.

The target temperature D0 of the refrigerator R can be set to be changeable within a predetermined range, and the first low temperature DL1 can be fixed to the same value regardless of the set value of the target temperature D0.

The target temperature D0 of the refrigerator R is set to be changeable within a predetermined range, and in the antifreeze mode, the heating start temperature don that starts driving the heating device 4 and the heating stop that stops driving the heating device 4. The temperature doff can be set respectively, and the heating start temperature don and the heating stop temperature doff can be fixed to the same value regardless of the set value of the target temperature D0.

In the normal refrigeration mode, a target temperature zone having a predetermined temperature range including the target temperature D0 is set, and the cooling start temperature Don for starting the driving of the cooling device 3 is set to the upper threshold of the target temperature zone, and the cooling device 3 is set. The cooling stop temperature Doff for stopping the driving of the heating device 4 is set to the lower threshold value of the target temperature range, and the heating stop temperature doff for stopping the driving of the heating device 4 is set to the upper threshold value when the target temperature D0 is set to the lower limit value. Can be matched.

A circulation fan 16 for circulating the air in the refrigerator R is provided, and the circulation fan 16 can be constantly driven in the antifreeze mode.

In the present invention, while the cooling device 3 is stopped in the normal refrigerating mode, when the state where the internal temperature D is the first low temperature DL1 or less continues for the first low temperature time TL1 or more, the internal R is set by the heating device 4. Changed to shift to the anti-freezing mode to heat. That is, the actual temperature of the refrigerator R in which the storage P is housed is directly detected, and the presence or absence of the possibility of freezing of the storage P is determined based on the temperature, and usually only when there is a risk of freezing. Changed to shift from refrigeration mode to anti-freezing mode. When the presence or absence of the possibility of freezing is determined based on the actual internal temperature D, the determination can be made more accurately than in the case of determining based on the outside air temperature or the like. When it is accurately determined whether or not there is a risk of freezing, when there is a risk of freezing, it is possible to shift to the anti-freezing mode and drive the heating device 4 to reliably prevent freezing. Further, when there is no risk of freezing, it is possible to avoid the transition to the anti-freezing mode, avoid unnecessary driving of the heating device 4, and reduce the power consumption thereof.

Further, in the present invention, the first low temperature time TL1 is set in addition to the first low temperature DL1, and the state in which the internal temperature D is the first low temperature DL1 or less continues for the first low temperature time TL1 or more, and then the normal refrigeration mode is started. Changed to shift to anti-freeze mode. In other words, if the temperature D in the refrigerator temporarily falls below the first low temperature DL1, the mode does not shift to the antifreeze mode. Even if the temperature D in the refrigerator temporarily falls below the first low temperature DL1, if the temperature exceeds the first low temperature DL1 immediately after that, the storage P is unlikely to freeze, and the heating device 4 is used to keep the inside of the refrigerator. The need to heat is low. According to the present invention, it is possible to avoid unnecessary driving of the heating device 4 in such a case and reduce its power consumption.

When the internal temperature D drops to the second low temperature DL2, which is even lower than the first low temperature DL1, the risk of freezing of the storage P becomes higher. Therefore, in the present invention, when the internal temperature D drops to the second low temperature DL2, the mode shifts to the antifreeze mode when the state continues for the second low temperature time TL2 or more, which is shorter than the first low temperature time TL1. did. As a result, the mode can be quickly shifted to the anti-freezing mode to drive the heating device 4, and the storage P can be reliably prevented from freezing.

In the anti-freezing mode, when the temperature inside the refrigerator D is the first high temperature DH1 or higher for the first high temperature time TH1 or longer while the heating device 4 is stopped, the normal refrigerating mode is restored. That is, even in the antifreeze mode, the actual temperature of the refrigerator R in which the storage P is housed is directly detected, and the presence or absence of the possibility of freezing of the storage P is determined based on the temperature, and the risk of freezing is determined. Changed to return to normal refrigeration mode only when there is no. When the presence or absence of the possibility of freezing is determined based on the actual temperature D in the refrigerator, the determination can be made accurately as described above. If the risk of freezing is eliminated, it is possible to return to the normal refrigerating mode, avoid unnecessary driving of the heating device 4, and reduce its power consumption. Further, if the risk of freezing is still not eliminated, the freezing of the storage P can be continuously prevented by maintaining the antifreezing mode.

Further, in the present invention, the first high temperature time TH1 is set in addition to the first high temperature DH1, and the state in which the internal temperature D is the first high temperature DH1 or more continues for the first high temperature time TH1 or more, and then the antifreeze mode is started. Changed to return to normal refrigeration mode. In other words, if the temperature inside the refrigerator D temporarily becomes the first high temperature DH1 or higher, the normal refrigerating mode is not restored. Even if the internal temperature D temporarily rises above the first high temperature DH1, if it falls below the first high temperature DH1 immediately thereafter, it cannot be said that the risk of freezing of the storage P has been eliminated. According to the present invention, the antifreeze mode can be maintained in such a case to continue to prevent the storage P from freezing.

When the temperature D in the refrigerator rises to the second high temperature DH2, which is higher than the first high temperature DH1, the risk of freezing of the storage P is almost eliminated. Therefore, in the present invention, when the internal temperature D rises to the second high temperature DH2, the normal refrigerating mode is restored when the state continues for the second high temperature time TH2 or more, which is shorter than the first high temperature time TH1. did. As a result, it is possible to quickly return to the normal refrigerating mode and restart the cooling of the internal R, and avoid unnecessary driving of the heating device 4.

When the first low temperature DL1 is fixed to the same value regardless of the target temperature D0, it is possible to shift from the normal refrigeration mode to the antifreeze mode or maintain the normal refrigeration mode under the same conditions at all times. Contrary to the present invention, when the first low temperature DL1 depends on the set temperature D0, for example, when the difference between the set temperature D0 and the first low temperature DL1 is kept constant, the set temperature D0 is set relatively high. When this is done, the first low temperature DL1 also rises, and even if there is no risk of the storage P being frozen, the mode shifts to the antifreeze mode, and the heating device 4 wastes power. On the other hand, in the present invention, since the first low temperature DL1 is always fixed to the same value, it is possible to accurately determine whether or not there is a risk of freezing regardless of the set value of the set temperature D0.

In the present invention, the heating start temperature don and the heating stop temperature doff by the heating device 4 can be fixed to the same value regardless of the target temperature D0. Contrary to the present invention, when the heating start temperature don and the heating stop temperature doff depend on the set temperature D0, for example, when both temperatures don and doff are set to values above and below the set temperature D0, the antifreeze mode is used. Although there is an advantage that the internal temperature D can be maintained in the vicinity of the set temperature D0, there is a disadvantage that the driving time of the heating device 4 becomes long and the power consumption increases, especially when the set temperature D0 is relatively high. .. On the other hand, in the present invention, the heating start temperature don and the heating stop temperature doff are fixed to the same value regardless of the set value of the set temperature D0, so that the power consumption of the heating device 4 may increase above a certain level. It is excellent in energy saving.

When the heating stop temperature doff for stopping the driving of the heating device 4 matches the upper threshold value when the target temperature D0 is set to the lower limit value, that is, the lowest value of the upper threshold value, the internal temperature D in the antifreeze mode However, it is possible to prevent the temperature exceeding the target temperature range from being exceeded due to the influence of the heat generated by the heating device 4. That is, in the antifreeze mode, the storage P in the refrigerator R is heated to the lowest value of the upper threshold value to surely prevent the storage P from freezing, and the storage P in the storage R is kept in a low temperature state not exceeding the target temperature range. It can be stored and does not cause an excessive increase in the internal temperature D or an increase in the power consumption of the heating device 4.

When the circulation fan 16 is constantly driven in the anti-freezing mode, the heat of the heating device 4 can be distributed to the entire chamber R, and the temperature unevenness of the chamber R can be eliminated. As a result, it is possible to prevent inconveniences such as freezing only a part of the storage P in the chamber R without being heated, or excessively heating only a part of the storage P near the heating device 4. it can.

It is a flowchart about the operation mode of the low temperature storage which concerns on this invention, and the switching thereof. It is a front view when the door is opened which shows the schematic structure of a low temperature storage. It is a figure which shows the control system of a low temperature storage. It is a timing chart which shows the transition of the temperature inside the refrigerator and the driving state of each part in a normal refrigerating mode. It is a timing chart which shows the transition of the temperature inside the refrigerator and the driving state of each part in the antifreeze mode. It is a flowchart which shows the transition condition from the normal refrigeration mode to the antifreeze mode. It is a flowchart which shows the condition of returning from an antifreeze mode to a normal refrigerating mode. It is a timing chart which shows the case of transitioning to the antifreeze mode based on the first transition condition. It is a timing chart which shows the case of transitioning to the antifreeze mode based on the second transition condition. It is a timing chart which shows the case of returning to the normal refrigerating mode based on the 1st return condition. It is a timing chart which shows the case of returning to the normal refrigerating mode based on the 2nd return condition. It is a timing chart which shows the case where there is a difference in the temperature inside the refrigerator of a normal refrigerating mode and an antifreezing mode.

(Example) Examples of the low temperature storage according to the present invention are shown in FIGS. 1 to 12. In FIG. 2, the low-temperature storage includes a storage main body 1 made of a vertically long rectangular parallelepiped box having an opening on the front surface, and a door 2 for opening and closing the opening of the storage main body 1. Storage P such as brown rice and fruits and vegetables can be stored in the storage R surrounded by the storage body 1 and the door 2. The interior R is cooled by the cooling device 3 installed on the upper surface of the storage main body 1 in the normal refrigerating mode, and a plurality of heaters arranged along the inner wall surface of the storage main body 1 in the antifreezing mode. It is heated by the heating device) 4. Details of both operation modes will be described later. The cooling device 3 is housed in a square box-shaped cover 5 having a group of vents. An operation panel 6 is provided on the front surface of the cover 5 for the user to input the target temperature D0 of the inside R and the like.

On one side of the cover 5, a cooling chamber 10 communicating with the internal R via a suction port 8 and an air outlet 9 is formed. The cooling chamber 10 is surrounded by a heat insulating wall except for the lower surface facing the interior R, and is insulated from the space inside the cover 5. In FIG. 3, the cooling device 3 includes a compressor 11, a condenser 12, an expansion unit 13, an evaporator 14, and a condenser fan 15 for cooling the condenser 12, which are connected by a refrigerant pipe. The evaporator 14 is arranged in the cooling chamber 10. A circulation fan 16 is arranged in the cooling chamber 10. When the circulation fan 16 is driven together with the cooling device 3, the air in the refrigerator R is sucked into the cooling chamber 10 from the suction port 8 and cooled while passing through the evaporator 14, and is cooled from the outlet 9 to the refrigerator R. Blow out.

In FIG. 3, the control device 20 uses the cooling device 3 (compressor 11 and the compressor 11) based on the target temperature D0 of the refrigerator R input from the operation panel 6 and the detection value of the temperature sensor 21 that detects the temperature D in the refrigerator. The condenser fan 15), the heater 4, and the circulation fan 16 are controlled (details will be described later). The temperature sensor 21 is arranged on the upstream side of the evaporator 14 in the cooling chamber 10, and the air immediately after being sucked into the cooling chamber 10 from the chamber R through the suction port 8 (before passing through the evaporator 14). Detects the temperature of air).

The low temperature storage according to this embodiment includes two operation modes, a normal refrigeration mode and an antifreeze mode. As shown in the flowchart of FIG. 1, when the power of the low temperature storage is turned on, the control device 20 first sets the operation mode to the normal refrigeration mode (step S1). If the first transition condition or the second transition condition described later is satisfied (YES in step S2 or step S3) during the operation in the normal refrigeration mode, the control device 20 switches the operation mode to the antifreeze mode (step S4). The user is notified that the anti-freezing mode has been switched to, for example, by using the display unit of the operation panel 6. Further, if the first return condition or the second return condition described later is satisfied during the operation in the antifreeze mode (YES in step S5 or step S6), the control device 20 switches the operation mode to the normal refrigeration mode (step S1). ..

In the normal refrigerating mode, the control device 20 intermittently drives the cooling device 3 to maintain the internal temperature D in the vicinity of the target temperature D0. Specifically, as shown in FIG. 4, a target temperature zone of (D0 ± f) ° C. centered on the target temperature D0 is set, and the upper threshold value of the temperature zone, that is, (D0 + f) ° C., is set by the cooling device 3. The cooling start temperature Don for starting the drive is set, and the lower threshold value of the temperature range, that is, (D0−f) ° C. is set as the cooling stop temperature Doff for stopping the drive of the cooling device 3. The control device 20 repeats the control of driving the cooling device 3 when the internal temperature D rises to the cooling start temperature Don and stopping the cooling device 3 when the internal temperature D drops to the cooling stop temperature Doff. Keep the temperature D within the target temperature range. The circulation fan 16 is driven at the same time as the cooling device 3 and is on / off controlled at the same timing as the device 3. In this embodiment, the range of the target temperature D0 that can be input from the operation panel 6 is set to 2 to 15 ° C. Further, the temperature range f for determining the target temperature zone was set to 2 ° C. For example, when the target temperature D0 is set to 2 ° C., the cooling start temperature Don is 4 ° C., and the cooling stop temperature Doff is 0 ° C.

When foodstuffs such as fruits and vegetables with high water content are frozen, their cells are destroyed by ice crystals, and the quality is greatly impaired. In order to prevent this, the low temperature storage according to this embodiment is provided with an antifreeze mode. In the antifreeze mode, the control device 20 intermittently drives the heater 4 while the cooling device 3 is stopped. Specifically, as shown in FIG. 5, the heating start temperature don and the heating stop temperature doff are set respectively (don <doff), and when the internal temperature D drops to the heating start temperature don, the heater 4 is energized. Then, when the internal temperature D rises to the heating stop temperature doff, the energization of the heater 4 is stopped. The circulation fan 16 is always driven regardless of the energized state of the heater 4. In this embodiment, the heating start temperature don was set to 2 ° C, and the heating stop temperature doff was set to 4 ° C. The cooling start temperature Don and the cooling stop temperature Doff in the normal refrigeration mode described above are variables that change according to the value of the target temperature D0, but the heating start temperature don and the heating stop temperature doff in the antifreeze mode are the targets. It is a constant set regardless of the temperature D0.

If the temperature D inside the refrigerator drops more than necessary during the operation of the low-temperature storage in the normal refrigerating mode and there is a risk that the storage P may freeze, the operation mode is switched to the antifreeze mode and the inside R Needs to be heated by the heater 4. The first transition condition and the second transition condition are set respectively in order to accurately determine the necessity of heating by the heater 4, that is, the necessity of transition to the antifreeze mode. Here, the first transition condition is simply that, while the compressor 11 (cooling device 3) is stopped, a low temperature state having a slightly high risk of freezing continues for a relatively long time. The second transition condition is that while the compressor 11 is stopped, a low temperature state with a considerably high risk of freezing continues for a relatively short period of time. In the present invention, a low temperature state having a slightly high risk of freezing is defined as a "state of a first low temperature DL1 or less", and a low temperature state having a considerably high risk of freezing is defined as a "state of a second low temperature DL2 or less". Is defined as (DL1> DL2). The first low temperature DL1 and the second low temperature DL2 are constants set independently of the variable target temperature D0. In this embodiment, the first low temperature DL1 was set to 2 ° C and the second low temperature DL2 was set to -2 ° C. Further, in the present invention, a relatively long time is defined as "first low temperature time TL1", and a relatively short time is defined as "second low temperature time TL2" (TL1> TL2). In this embodiment, the first low temperature time TL1 was set to 60 minutes and the second low temperature time TL2 was set to 10 seconds.

The first transition condition and the second transition condition will be described in detail with reference to the flowchart of FIG. In the control shown in the figure, a first timer that clocks the first time T1 and a second timer that clocks the second time T2 are used. When the compressor 11 is stopped and the temperature D in the refrigerator drops to the first low temperature DL1 (2 ° C.) during the operation of the low temperature storage in the normal refrigerating mode (YES in steps S11 and S12), the control device 20 is set to the first. Time counting by one timer is started (step S13). The cooling stop temperature Doff at which the compressor 11 stops changes according to the value of the target temperature D0 of the chamber R. When the target temperature D0 and the cooling stop temperature Doff are relatively high, the compressor 11 is stopped before the internal temperature D drops to the first low temperature DL1, and the target temperature D0 and the cooling stop temperature Doff are relatively low. The compressor 11 is stopped after the internal temperature D drops to the first low temperature DL1. When the target temperature D0 is 4 ° C., the cooling stop temperature Doff is 2 ° C., which is the same as the first low temperature DL1, and therefore YES is obtained at the same time in steps S11 and S12.

In steps S14 to S16 following step S13, whether or not the internal temperature D rises and exceeds the first low temperature DL1 (2 ° C.) in order from the top, the internal temperature D is the second low temperature DL2 (-). Whether or not the temperature has dropped to 2 ° C.) and whether or not the first time T1 has reached the first low temperature time TL1 (60 minutes) are monitored, and a YES is waited for in any of these three steps. If YES is obtained in step S14 prior to step S15 and step S16, that is, if the internal temperature D rises and exceeds the first low temperature DL1, the control device 20 stops the time counting by the first timer. (Step S17), the process returns to step S11. That is, the operation mode of the low temperature storage is maintained in the normal refrigeration mode. In this embodiment, since the lower limit of the target temperature D0 of the chamber R is 2 ° C., the lower limit of the cooling start temperature Don at which the compressor 11 starts is 4 ° C. Therefore, the compressor 11 does not start before the result becomes YES in step S14 (the internal temperature D exceeds the first low temperature DL1).

If YES is set in step S16 prior to step S14 and step S15, that is, if the first low temperature time TL1 (60 minutes) has elapsed from the start of timekeeping in step S13, the control device 20 performs timekeeping by the first timer. At the same time as stopping (step S18), the operation mode is shifted from the normal refrigeration mode to the antifreeze mode (step S19). Here, the operation mode is switched based on the first transition condition.

If YES is set in step S15 prior to step S14 and step S16, that is, if the internal temperature D drops to the second low temperature DL2 (-2 ° C.), the control device 20 clocks by the first timer. While continuing, the time counting by the second timer is started (step S20). If the temperature inside the refrigerator D rises and exceeds the second low temperature DL2 before the second low temperature time TL2 (10 seconds) elapses after starting this timekeeping (NO in step S22, YES in step S21). ), The control device 20 stops the time counting by the second timer (step S23), and returns to the loop of the above-mentioned steps S14 to S16. On the contrary, when the second low temperature time TL2 elapses without the internal temperature D exceeding the second low temperature DL2 (NO in step S21, YES in step S22), the control device 20 uses the second timer and the first. The time counting by the timer is stopped (step S24 / step S18), and the operation mode is changed from the normal refrigeration mode to the antifreeze mode (step S19). Here, the operation mode is switched based on the second transition condition.

During the operation of the low-temperature storage in the anti-freezing mode, if the risk of freezing of the storage P is eliminated due to an increase in the temperature outside the low-temperature storage, the operation mode may be returned to the normal refrigeration mode. preferable. The first return condition and the second return condition are set respectively in order to accurately determine whether or not the return to the normal refrigeration mode is possible. Here, the first return condition is simply that, while the heater 4 is stopped, a temperature state in which the risk of freezing is sufficiently low continues for a relatively long period of time. Further, the second return condition is that the temperature state in which there is no risk of freezing continues for a relatively short time while the heater 4 is stopped. In the present invention, a temperature state in which the risk of freezing is sufficiently low is defined as a "state of a first high temperature DH1 or higher", and a temperature state in which there is no risk of freezing is defined as a "state of a second high temperature DH2 or higher". "(DH1 <DH2). The first high temperature DH1 and the second high temperature DH2 are constants set independently of the variable target temperature D0. In this embodiment, the first high temperature DH1 was set to 4 ° C. and the second high temperature DH2 was set to 6 ° C. Further, in the present invention, a relatively long time is defined as "first high temperature time TH1", and a relatively short time is defined as "second high temperature time TH2" (TH1> TH2). In this embodiment, the first high temperature time TH1 is set to 60 minutes, which is the same as the first low temperature time TL1, and the second high temperature time TH2 is set to 10 seconds, which is the same as the second low temperature time TL2.

The first return condition and the second return condition will be described in detail with reference to the flowchart of FIG. 7. Also in the control shown in the figure, a first timer that clocks the first time T1 and a second timer that clocks the second time T2 are used. When the heater 4 is stopped and the internal temperature D rises to the first high temperature DH1 (4 ° C.) during the operation of the low temperature storage in the antifreeze mode (YES in steps S31 and S32), the control device 20 is set to the first. Timekeeping by the timer is started (step S33). In this embodiment, since the heating stop temperature doff at which the heater 4 stops and the first high temperature DH1 are the same 4 ° C., steps S31 and S32 are YES at the same time.

In steps S34 to S36 following step S33, whether or not the internal temperature D has decreased to less than the first high temperature DH1 (4 ° C.) in order from the top, the internal temperature D is the second high temperature DH2 (6 ° C.). ), And whether the first time T1 has reached the first high temperature time TH1 (60 minutes) is monitored, and it waits for YES in any of these three steps. If YES is obtained in step S34 prior to step S35 and step S36, that is, if the internal temperature D drops below the first high temperature DH1, the control device 20 stops the time counting by the first timer ( Step S37), the process returns to step S31. That is, the operation mode of the low temperature storage is maintained in the antifreeze mode. In this embodiment, since the heating start temperature don for starting the energization of the heater 4 is 2 ° C., the heater 4 is set to YES in step S34 (the internal temperature D is lower than the first high temperature DH1). The energization to is never started.

If YES is set in step S36 prior to step S34 and step S35, that is, if the first high temperature time TH1 (60 minutes) has elapsed from the start of time counting in step S33, the control device 20 performs time counting by the first timer. At the same time as stopping (step S38), the operation mode is returned from the antifreeze mode to the normal refrigeration mode (step S39). Here, the operation mode is switched based on the first return condition.

If YES is obtained in step S35 prior to step S34 and step S36, that is, if the temperature inside the refrigerator D rises to the second high temperature DH2 (6 ° C.), the control device 20 continues timing by the first timer. With this, the time counting by the second timer is started (step S40). If the internal temperature D drops below the second high temperature DH2 before the second high temperature time TH2 (10 seconds) elapses after the start of this timekeeping (NO in step S42, YES in step S41). ), The control device 20 stops the time counting by the second timer (step S43), and returns to the loop of the above-mentioned steps S34 to S36. On the contrary, when the second high temperature time TH2 elapses without the internal temperature D exceeding the second high temperature DH2 (NO in step S41, YES in step S42), the control device 20 uses the second timer and the first. The time counting by the timer is stopped (step S44, step S38), and the operation mode is returned from the antifreeze mode to the normal refrigeration mode (step S39). Here, the operation mode is switched based on the second return condition.

An example of the temporal change of the internal temperature D and the driving state of each part of the low temperature storage is shown in the timing chart of FIG. Here, the target temperature D0 of the refrigerator R in the normal refrigerating mode is set to the lower limit of 2 ° C. Therefore, the cooling start temperature Don at which the compressor 11 (cooling device 3) starts is 4 ° C, and the cooling stop temperature Doff at which the compressor 11 stops is 0 ° C. In the timing charts described below, the temperatures D0, Don, and Doff are the same unless otherwise specified.

At the first time point t1, the internal temperature D drops to 0 ° C., which is the cooling stop temperature Doff, and the compressor 11 and the circulation fan 16 are stopped. At this time, since the temperature D in the refrigerator is equal to or lower than the first low temperature DL1 (2 ° C.), the control device 20 starts time counting by the first timer (steps S11 to S13 in FIG. 6). At the next time point t2, the temperature D in the refrigerator rises to the first low temperature DL1, that is, 2 ° C. Here, since the first low temperature time TL1 (60 minutes) has not elapsed from the start of the time measurement by the first timer (t2-t1 <60 minutes), the control device 20 stops the time measurement by the first timer and the low temperature storage. The operation mode of is maintained in the normal refrigerating mode (steps S14 and S17 in FIG. 6). At the next time point t3, the temperature inside the refrigerator D rises to the cooling start temperature Don, that is, 4 ° C., and the compressor 11 and the circulation fan 16 are started.

The control procedure at the time point t4 is the same as that at the time point t1 described above, but the rate of increase in the internal temperature D thereafter is slower than that at the time points t1 to t2. The main reason for the slow rise in temperature is the decrease in the outside temperature of the low temperature storage. At the next time point t5, as the first low temperature time TL1 (60 minutes) elapses from the start of timekeeping by the first timer, the control device 20 stops the timekeeping by the first timer and sets the operation mode to the antifreeze mode. The transition is made (steps S16, S18, S19 in FIG. 6). When the mode shifts to the antifreeze mode, the circulation fan 16 starts driving. At this time, since the internal temperature D is the heating start temperature don, that is, 2 ° C. or lower, the control device 20 starts energizing the heater 4. The energization of the heater 4 is continued until the temperature D in the refrigerator reaches the heating stop temperature doff, that is, t6 when the temperature reaches 4 ° C. When the heating stop temperature doff matches the cooling start temperature Don, that is, the upper threshold value of the target temperature zone, even in the antifreeze mode, the internal temperature D is suppressed from exceeding the target temperature zone, and the internal R is set. It can be maintained at a low temperature suitable for the storage P.

In cold regions in winter when the outside temperature is below 0 ° C, when the door 2 of the low temperature storage is opened, the low temperature outside air invades the inside R and the inside temperature D is significantly below the target temperature D0. There is. Even if the door 2 is closed after the intrusion of outside air, it is difficult to expect a natural rise in the internal temperature D because the outside air temperature is low. In order to raise the temperature D in the refrigerator to prevent the storage P from freezing, it is necessary to promptly shift the operation mode to the antifreezing mode.

In the timing chart shown in FIG. 9, the internal temperature D continues to decrease due to the intrusion of outside air into the internal R even after t11 when the internal temperature D decreases to 0 ° C. and the compressor 11 is stopped. .. The control device 20 starts the time counting by the first timer at the time point t11 (steps S11 to S13 in FIG. 6), and further, at the time point t12 when the internal temperature D drops to the second low temperature DL2 (-2 ° C.). 2 Starts time counting with a timer (steps S15 and S20 in FIG. 6). At the next time point t13, as the second low temperature time TL2 (10 seconds) elapses from the start of the time measurement by the second timer, the control device 20 stops the time measurement by the second timer and the first timer and sets the operation mode. The mode is shifted to the antifreeze mode (steps S22, S24, S18, S19 in FIG. 6). Since the internal temperature D at the time point t13 is below the heating start temperature don, that is, 2 ° C., the control device 20 starts energizing the heater 4. The energization of the heater 4 is continued until the temperature D in the refrigerator reaches the heating stop temperature doff, that is, t14 when the temperature reaches 4 ° C. At the next time point t15, the internal temperature D drops to the heating start temperature don, that is, 2 ° C., and the energization of the heater 4 is restarted.

In the example shown in FIG. 9, the antifreeze mode is set at the time point t13 when the second low temperature time TL2 (10 seconds) elapses from the time point t12 without waiting for the first low temperature time TL1 (60 minutes) to elapse from the time point t11. Has moved to. According to the low-temperature storage according to the present embodiment, when the internal temperature D drops to the second low temperature DL2 (-2 ° C), which is lower than the first low temperature DL1 (2 ° C), the antifreeze mode is promptly entered. It is possible to shift and start heating the inside R, which can surely prevent the storage P from freezing.

The timing chart of FIG. 10 shows an example of returning from the antifreezing mode to the normal refrigerating mode. Since the transition from the normal refrigeration mode to the antifreeze mode is mainly performed when the outside air temperature of the low temperature storage is low, immediately after the transition to the antifreeze mode, when the energization of the heater 4 is stopped, the internal temperature D becomes high. It often shows a gradual downward trend (time points t21 to t22). On the other hand, when the outside air temperature rises as compared with the transition to the antifreeze mode, the temperature D inside the refrigerator gradually rises even after the energization of the heater 4 is stopped (time points t23 to t24).

The control device 20 starts timing by the first timer at t23 when the heater 4 is stopped and the temperature D in the refrigerator rises to the first high temperature DH1 (4 ° C.) (steps S31 to S33 in FIG. 7). Then, at the time t24 when the first high temperature time TH1 (60 minutes) elapses from the start of the timekeeping, the timekeeping by the first timer is stopped and the operation mode is returned to the normal refrigeration mode (steps S36 and S38 in FIG. 7). -S39). Since the internal temperature D exceeds the cooling start temperature Don, that is, 4 ° C. at the time t24 when the normal refrigerating mode is returned, the control device 20 starts the compressor 11 and maintains the driving state of the circulation fan 16. At the next time point t25, the control device 20 stops the compressor 11 and the circulation fan 16 as the internal temperature D drops to the cooling stop temperature Doff, that is, 0 ° C.

The timing chart of FIG. 11 shows a case where the temperature D in the refrigerator rises at a faster pace than that of FIG. 10 while the heater 4 is stopped in the antifreeze mode. The control device 20 starts timing by the first timer at t31 when the heater 4 is stopped and the internal temperature D rises to the first high temperature DH1 (4 ° C.) (steps S31 to S33 in FIG. 7). Further, at the time t32 when the internal temperature D rises to the second high temperature DH2 (6 ° C.), the time counting by the second timer is started (steps S35 and S40 in FIG. 7). At the next time point t33, the control device 20 stops the time counting by the second timer and the first timer as the second high temperature time TH2 (10 seconds) elapses from the start of the time measurement by the second timer, and sets the operation mode. It is returned to the normal refrigeration mode (steps S42, S44, S38, S39 in FIG. 7). Since the internal temperature D at the time point t33 exceeds the cooling start temperature Don, that is, 4 ° C., the control device 20 starts the compressor 11 and maintains the driving state of the circulation fan 16. The driving state of the compressor 11 and the circulation fan 16 is continued until the time when the internal temperature D reaches the cooling shutdown temperature Doff, that is, 0 ° C., t34. At the next time point t35, the internal temperature D rises to the cooling start temperature Don, that is, 4 ° C., and the compressor 11 and the circulation fan 16 are restarted.

In the example shown in FIG. 11, the normal refrigeration mode is set at the time point t33 when the second high temperature time TH2 (10 seconds) elapses from the time point t32 without waiting for the first high temperature time TH1 (60 minutes) to elapse from the time point t31. Has returned to. According to the low temperature storage according to the present embodiment, when the internal temperature D rises to the second high temperature DH2 (6 ° C), which is higher than the first high temperature DH1 (4 ° C), the normal refrigerating mode is promptly returned. Then, the cooling of the internal R can be restarted.

As described above, the target temperature D0 of the chamber R can be set within the range of 2 to 15 ° C. The timing chart of FIG. 12 shows the change in the internal temperature D when the low temperature storage is operated with the target temperature D0 set to 8 ° C. The cooling start temperature Don is 6 ° C., which is 2 ° C. lower than the target temperature D0, and the cooling stop temperature Doff is 10 ° C., which is 2 ° C. higher than the target temperature D0. In the season when the outside air temperature is sufficiently higher than the target temperature D0, for example, in summer, the low temperature storage is normally operated in the refrigerating mode. As shown on the left side of the timing chart, the control device 20 controls the compressor 11 (cooling device 3) and the circulation fan 16 on and off to set the internal temperature D within the target temperature range of (D0 ± f) ° C. Keep inside.

On the other hand, when the outside air temperature drops to below freezing in winter or the like and the above-mentioned first transition condition or second transition condition is satisfied, the operation mode is automatically switched from the normal refrigeration mode to the antifreeze mode. As shown on the right side of the timing chart, the control device 20 controls the heater 4 on and off while constantly driving the circulation fan 16 to set the internal temperature D to the heating start temperature don (2 ° C.) and the heating stop temperature doff ( It is maintained during (4 ° C.) to prevent freezing of the storage P in the chamber R. It is technically possible to heat the chamber R to the target temperature range (6 to 10 ° C.) with the heater 4, but in this embodiment, from the viewpoint of energy saving, it is necessary to prevent freezing in the antifreeze mode. I try to do only minimal heating.

As described above, in the low-temperature storage according to the present embodiment, the actual temperature of the internal R in which the storage P is housed is directly detected, and the presence or absence of the possibility of freezing of the storage P is determined based on the temperature. Judging, the mode shifts from the normal refrigeration mode to the antifreeze mode only when there is a risk of freezing, and returns to the normal refrigeration mode when the risk of freezing disappears. When the presence or absence of the possibility of freezing is determined based on the actual internal temperature D, the determination can be made more accurately than in the case of determining based on the outside air temperature or the like. When it is accurately determined whether or not there is a risk of freezing, when there is a risk of freezing, it is possible to shift to the antifreeze mode and drive the heater 4 to reliably prevent freezing. Further, when there is no risk of freezing, the normal refrigerating mode can be maintained and the freezing prevention mode can be returned to the normal refrigerating mode to avoid unnecessary driving of the heater 4 and reduce its power consumption.

The low-temperature storage according to the above embodiment is provided with two operation modes, a normal refrigeration mode and an antifreeze mode, but the present invention is not limited to this, and for each foodstuff to be stored, for example, for brown rice and for fruits and vegetables. It may have a plurality of types of normal refrigeration modes. In this case, in each normal refrigerating mode, the settable range of the target temperature D0 of the chamber R, the temperature range f that determines the target temperature zone, and the like can be made different. Further, the circulation fan 16 may be constantly driven in the normal refrigerating mode. In particular, when the normal refrigeration mode for fruits and vegetables is implemented, the frost adhering to the evaporator 14 is vaporized by driving the circulation fan 16 while the compressor 11 is stopped, and the water vapor is sent to the chamber R. By feeding, the refrigerator R can be kept in a high humidity state suitable for storing fruits and vegetables. Further, the low temperature storage can be provided with two or more types of antifreeze modes. In this case, the heating start temperature don, the heating stop temperature doff, and the like can be made different in each anti-freezing mode. The first low temperature time TL1 and the first high temperature time TH1 do not have to be the same, and the second low temperature time TL2 and the second high temperature time TH2 do not have to be the same. The cooling device 3 and the heating device 4 are not limited to the refrigerator and the heater, and may be composed of, for example, a Perche element.

3 Cooling device 4 Heating device (heater)
16 Circulation fan 20 Control device 21 Temperature sensor R Inside D Inside temperature DL1 First low temperature DL2 Second low temperature DH1 First high temperature DH2 Second high temperature TL1 First low temperature time TL2 Second low temperature time TH1 First high temperature Time TH2 Second high temperature time D0 Target temperature Don Cooling start temperature Doff Cooling stop temperature don Heating start temperature doff Heating stop temperature

Claims (7)

A cooling device (3) for cooling the inside (R), a heating device (4) for preventing freezing to heat the inside (R), and a temperature sensor (21) for detecting the inside temperature (D). It is a low temperature storage equipped with
As operation modes, a normal refrigeration mode in which the cooling device (3) is intermittently driven, the warming device (4) is provided with a freeze prevention mode for intermittently driving,
From a predetermined first low temperature (DL1), a second low temperature (DL2) lower than the first low temperature (DL1), a predetermined first low temperature time (TL1), and the first low temperature time (TL1). A short second low temperature time (TL2) is set respectively,
In the normal refrigeration mode, the during the stop of the cooling device (3), said temperature sensor (21) the in-compartment temperature (D) is the first low temperature (DL1) following conditions said first detected by In addition to the case where the low temperature time (TL1) or more continues , in the normal refrigeration mode, the state in which the internal temperature (D) is equal to or lower than the second low temperature (DL2) while the cooling device (3) is stopped. the second low temperature time (TL2) or lasted even when, low-temperature storage, characterized in that the transition to the freeze prevention mode. A first high temperature (DH1) higher than the first low temperature (DL1) and a predetermined first high temperature time (TH1) are set respectively.
In the antifreeze mode , the state in which the temperature inside the refrigerator (D) detected by the temperature sensor (21) is equal to or higher than the first high temperature (DH1) while the heating device (4) is stopped is the first. 1 The low temperature storage according to claim 1, which returns to the normal refrigeration mode when the high temperature time (TH1) or more continues. A second high temperature (DH2) higher than the first high temperature (DH1) and a second high temperature time (TH2) shorter than the first high temperature time (TH1) are set respectively.
Wherein the anti-freeze mode, the during the stop of the heating device (4), when the in-compartment temperature (D) is the second high temperature (DH2) or more states continues the second high temperature time (TH2) or Also, the low temperature storage according to claim 2, which returns to the normal refrigeration mode. The target temperature (D0) in the refrigerator (R) is set to be changeable within a predetermined range.
The low temperature storage according to any one of claims 1 to 3, wherein the first low temperature (DL1) is fixed to the same value regardless of the set value of the target temperature (D0). Target temperature (D0) is set to be changed within a predetermined range in said chamber (R),
In the anti-freezing mode, a heating start temperature (don) for starting the driving of the heating device (4) and a heating stop temperature (doff) for stopping the driving of the heating device (4) are set, respectively. Cage,
The low temperature according to any one of claims 1 to 4, wherein the heating start temperature (don) and the heating stop temperature (doff) are fixed to the same value regardless of the set value of the target temperature (D0). Storage. In the normal refrigeration mode, a target temperature zone having a predetermined temperature range including the target temperature (D0) is set.
The cooling start temperature (Don) for starting the driving of the cooling device (3) is set to the upper threshold value of the target temperature zone, and the cooling stop temperature (Doff) for stopping the driving of the cooling device (3) is set. , It is set to the lower threshold of the target temperature range,
Wherein the heating stop temperature of stopping the driving of the heating device (4) (doff) is, low-temperature storage according to claim 5 match on threshold value when set the target temperature (D0) to the lower limit value .. A circulation fan (16) for circulating the air in the refrigerator (R) is provided.
The low temperature storage according to any one of claims 1 to 6 , wherein the circulation fan (16) is constantly driven in the antifreeze mode .

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